Oxygen vacancy-modified fast charge transport channels at the interface of bismuth S-scheme heterojunctions promoting photocatalytic performance

Abstract

While oxygen vacancies (Ov) in single semiconductor photocatalysts have been extensively studied, investigations into and comprehensive understanding of electron transfer and intrinsic mechanisms of Ov in heterojunction photocatalysts—particularly S-scheme heterojunctions—remain inadequate. In this study, novel oxygen vacancy-rich Ov-Bi₄O₇/Bi_3.64Mo_0.36O_6.55 (MOB) S-scheme heterojunction catalysts were designed and constructed. These catalysts combine oxygen vacancy-rich Bi₄O₇ with Bi_3.64Mo_0.36O_6.55 (BMO) to enhance interfacial charge transfer across the heterojunction and generate active centers enriched with oxygen vacancies. The optimized MOB-32 heterojunction achieved 97.6% degradation of tetracycline (TC) under light irradiation. The introduction of Ov improved the local electronic structure and microenvironment of the S-scheme heterojunction. Femtosecond transient absorption spectroscopy (Fs-TAS) reveals that Ov introduces additional charge transport pathways, which enhance the efficiency of charge separation. This study provides insights into the dynamics of photogenerated carriers at interfaces modulated by oxygen vacancies, contributing to the development of efficient S-scheme photocatalysts.